Anthony Liguori wrote:
This could correspond to a:
void *cpu_physical_memory_map(target_phys_addr_t addr, ram_addr_t
size, int is_write);
void cpu_physical_memory_unmap(target_physical_addr_t addr, ram_addr_t
size, void *mapping, int is_dirty);
A really nice touch here, and note this is optional and can be a follow
up series later, would be to use the mapping itself to encode the
physical address and size so the signatures were:
void *cpu_physical_memory_map(target_phys_addr_t addr, ram_addr_t size,
int flags);
void cpu_physical_memory_unmap(void *mapping);
flags could be PHYS_MAP_READ and/or PHYS_MAP_WRITE.
In unmap, you could check to see if the address is in phys_ram_base ...
phys_ram_size. If so, you can get the physical address.
If you maintained a list of mappings, you could then search the list of
mappings based on the physical address and check the flags to see if a
flush was required.
If you also stored the address in the list, you could search on unmap if
the address was not in phys_ram_base .. phys_ram_size (which implies a
bounce buffer).
Another potential optimization would be to provide a mechanism to
explicitly set the dirty range of a physical mapping. For instance:
cpu_physical_memory_map_set_dirty(void *start, ram_addr_t size);
That would let you only copy the data that actually needed to. I think
we can probably ignore this later optimization for a while though.
Regards,
Anthony Liguori
The whole dma.c thing should not exist. If we're going to introduce a
higher level API, it should be a PCI DMA API.
Something like virtio could use this API directly seeing as it doesn't
really live on a PCI bus in real life.
Regards,
Anthony Liguori
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